It’s been a rite of passage for decades. Every summer, over a thousand British Jewish teenagers travel to Israel on youth movement tours, led by young madrichim (leaders) and supported and managed by UJIA and the Jewish Agency.

For those who remember going on ‘tour,’ or leading it, or watching our children return from it, we know how transformative it is. We see it and feel it — somehow its magic seems to kindle a Jewish spark in a way that little else can.

Yet academic debate about its impact persists, particularly in the US. Researchers at Brandeis University responsible for studying the Birthright Israel programme have long argued in favour of its transformative effects. Birthright has sent over 650,000 young Jews on free trips to Israel over the past two decades, and Brandeis research has found that Birthright participants are more likely than others to feel a strong connection to Israel, marry Jews, have Jewish friends and join synagogues.

Birthright’s success, they argue, “suggests that an even closer, more personal and meaningful relationship between Israel and the American Jewish Diaspora, may be on the horizon.”

Yet if such a change is happening, the more general research on American Jews’ attachment to Israel is not picking it up. The Pew Research Center’s 2013 study of Jewish Americans provides clear evidence of declining levels of attachment to Israel by age. To cite just one example, where 53 per cent of those aged 65 and above regard Israel to be an essential part of being Jewish, that proportion falls by each age band measured, reaching just 32 per cent among 18-29-year-olds.

Researchers call this the “distancing hypothesis,” a theory established in the 1990 and 2000s. “The patterns in Israel attachment associated with age certainly point to the possibility of broad-scale erosion among the American Jewish population over the medium term” argued American Jewish sociologist Professor Steven M. Cohen in 1996. The pollster, Frank Luntz, writing about young American Jews in a 2003 study, similarly concluded that their “association with Israel is frighteningly weak and ill-defined.” And this narrative persists; despite all the investments in Israel education, Jewish leaders on both sides of the Atlantic continue to express concern about it today.

Part of the debate is academic. How does one go about assessing impact? What impact is one looking for? To what extent can indicators found several years after individuals have participated in an Israel programme be attributed to their attendance on that particular programme? How do we account for the effects of other factors — not least the political climate? Would declining levels of attachment observed across generations be even sharper if Israel programmes were weaker or didn’t exist?

It’s a complicated conundrum. Intuitively, we know the power of these programmes – we see it time and again. But empirically, it’s difficult to prove, particularly if we’re looking for long-term impact.

By contrast, the evidence about the positive effects of long-term, gap-year programmes in Israel is far more conclusive. Thus my conclusion is that if we really want our children to attach to Israel over time, Israel summer tours are critical, but insufficient. As powerful as they are, they need to sit within a much broader, and sharper, Israel education strategy.

I have been strengthened in this conviction recently after seeing one finding from JPR’s recent study of young Jews in Europe. In it, we found evidence of the distancing hypothesis across Europe too — that despite all the investments in their Israel education, young European Jews are still less attached to Israel than their elders.

But intriguingly, we found that they are also less attached to the countries in which they live, and indeed, to Europe. So perhaps the issue is not simply about Israel, but about attachment to “place” in general. Perhaps young people just don’t attach to place in the ways older people do.

The fact that they have grown up in a more open world, with easy access to other countries and cultures, lends some credence to this idea. The added fact that they can use technology to easily maintain any personal connections they build across the globe serves to strengthen it.

So perhaps part of the reason why connections to Israel are weakening over generations is because place in general doesn’t sufficiently resonate with young people. If that’s true, it in no way diminishes the case for Israel summer tours, but the wider Israel education strategies and methods we deploy may well be ripe for review.

Jonathan Boyd is executive director of the Institute for Jewish Policy Research (JPR)